[TowerTalk] Rai Beam

Mon, 10 Apr 2000 14:05:30 -0400

Hi Joe,
  Reviewing a few known facts, i remember that the ZL Special, a dual
driven
phased array, has a gain of about 3 dbd. The 2 element yagi produces a
gain
of 4.5-5 dbd, the 2 element quad produces a gain of 5-5.5 dbd, the 3
element 
yagi produces a gain of about 6 dbd, the 4 element yagi- about 7 dbd, the
5 
element yagi- about 8 dbd, so on. Beyond about that limit, the gain
starts to fall
below 1 db per element.
  I don't believe for a second, that the 2 element Raibeam produces a
gain of 8
dbi, which translates into 5.9 dbd., but for the sake of the arguement,
lets assume
that it does, for a moment. (Does anyone know how the Raibeam differs
from
the ZL Special?).
  First and foremost, the advantage that one enjoys with most antennas
with
directional characteristics, it that they are raised to a height that
places their
lower lobe  in the range of angles of radiation that are appropriate to a
particular
path. Even a dipole would perform well under such circumstances. Its
therefore,
not surprising that "trapped" tribanders with typical gain figures of
1-1/2 to 3 dbd
would also perform well. Likewise, the ZL Special, 2 element yagis,etc.
The 
differences between all these antennas are only a few db. Without a
reference
antenna for comparison, most of us would be hard pressed to even know
that there
was a difference, except intellectually. A difference of 1 db is so
insignifiicant that
even under closely and carefully controlled conditions, most of us could
only just
barely discern that level of difference between two signals. A difference
of 3 db isn't
remarkable( to quote Bill Orr), 5 db is a worthwhile difference(again, to
quote Orr), 
and a difference of 10 db, is a new level of performance, but still only
the difference
between an s-9 signal and one 10 db above s-9, IF, the "S" meter is
accurately
calibrated. 
  I will continue this in PART 2.  73 for now, Roy Lincoln WA4DOU
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On Mon, 10 Apr 2000 19:14:38 -0400 Joe Reisert <jreisert@jlc.net> writes:
> 
> To Interested Antenna Buffs,

> 
> 2. If it is true gain, we better all dump our antenna software, get 
> a 
> Raibeam and take down those big beams we are now using. Greater than 
> 8 dBi 
> gain in "free space" on 2-element a tri-bander using only an eight 
> foot 
> (0.12 wavelength on 20-meters) boom is mighty impressive. 
> Furthermore the 
> pattern in the ad infers a F/B ratio of almost 30 dBs!
> 
> Is this antenna patented? If so, what is the patent number so I can 
> get a 
> copy and be enlightened.
> 
> I'm anxiously awaiting the new antenna gain theory!
> 
> Joe, W1JR

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